The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A propulsion unit for an aircraft comprising a dual flow turbojet engine mounted inside in a nacelle delimiting a flow tunnel for a secondary flow can be mounted in various locations of the airplane while being attached to a mast belonging to the structure thereof.
It can thus be suspended under the wings, fastened to the fuselage, or mounted in the tail unit using attachment means that make it possible in particular to transmit the mechanical loads between the engine and the airplane structure to that wing, loads generated by the engine and loads coming from the nacelle transmitted by the engine during its various operating states.
The loads to be taken into consideration are oriented along the three main directions (forces and stresses). These are in particular the loads per unit of mass or inertia loads of the engine, its thrust, the aerodynamic loads, and the loads due to incidental or accidental operation (fan blade off, crash, etc.). The loads to be transmitted also comprise the reaction of the rotational torque around the engine shaft.
These attachment means must also absorb the deformations undergone by the engine during the different flight phases, in particular due to the dimensional variations due to the heat expansions or contractions and mechanical biases.
One suspension mode, for example, consists of attaching the engine to a mast arranged between the turbojet engine and the wing of the aircraft in the form of an elongated and rigid box capable of transmitting the loads (forces and stresses) in the three axial, lateral and vertical directions between the turbojet engine and the structure of the aircraft, the axis being that of the engine.
This mast, which extends in a vertical plane passing through the longitudinal axis of the engine, comprises suspension means for the engine through which all of the loads (forces and stresses) transmitted between the engine and the aircraft pass.
These suspension means comprise an upstream engine hanger in particular fastened on the intermediates casing of the turbojet engine and a downstream engine hanger in particular fastened on the exhaust casing of the turbojet engine.
These hangers are mounted on the aforementioned casings by means of clevis mounts 100 mounted on the casings, as illustrated in one particular example of the intermediate casing 120 of the prior art in FIG. 3.
In this figure, one can see that a clevis mount 100 is fastened on the outer shroud 121 of the intermediate casing 120 by fastening means 160 radially passing through the outer shroud of the casing 120.
These fastening means 160 comprise screwing means of the nut screw type.
These fastening means also pass through the outlet guide vanes 125 fastened to the intermediate casing 120 inasmuch as the clevises 100 are mounted across from those vanes 125.
However, such an assembly of the clevis mounts 100 on a casing 120 is not satisfactory.
The strains exerted at the interface between the intermediate casing 120 and the clevis mount 100 can create a deterioration of the composite structure, such as delamination, in the casing frame made from a composite material.
The reliability of the assemblies of clevis mounts on the casing is thereby affected.
This assembly also requires taking down the hangers and therefore the engine if one wishes to disassemble a rectifier vane 125.
The present disclosure is designed to offset the aforementioned problems.
The present disclosure provides a simple, effective and inexpensive solution to these problems.
It is also desirable to propose an attachment assembly capable of eliminating any connection between the flow rectifying vanes and the clevis mounts of the hanger inserted between the propulsion unit and the mast designed to support it.